Instrumentation Kernel Code

Description:

• One of the main ideas of this project is to fully characterize the performance of network estimators using application level code. However, our approach started out looking at the kernel level, and we would like to see the impact of TCP/IP stack on the dispersion of packets, such that one-way delay, available bandwidth estimation, and other techniques can be used robustly.

• Therefore, we started the project working on some kernel hooks that are going to be used to estimate the impact of the IP queue and other system overhead on the packet dispersion. We developed an initial kernel hook on FreeBSD kernel at (if_ethersubr.c). The idea was to obtain the packet dispersion at the ethernet level (to obtain a good estimation of the interrupt coalescing). Later this dispersion is going to be compared with other hooks in the IP and UDP layers, and finally at the application code
  

• The initial code can be found here.

• The second version is ready - it contains FreeBSD kernel hooks to capture the packet as it goes from ethernet to ip layer and through udp layer [README.freebsd] [FreeBSD 5.4 patch]

• Linux version of kernel hooks [Linux 2.4.20 patch] [Linux 2.6.12 patch]

• Final version of the instrumentation code in a bundle [microtools-release01.tar.gz]
• Distributed under the Internet2 Open Source License